In dialysis machines, heating of dialysis fluid is usually realized as an ohmic heating element to which a heating control applies mains voltage to switch the heating element on or to disconnect the heating element from the mains voltage in order to switch it off.
The heating power can be set and adapted to the different rated voltages to split the heater into a plurality of heating elements or to control the heating elements via a phase angle control. Phase angle controls are, however, complicated and moreover have problems with electromagnetic irradiation. There is moreover a substantial power loss in the electronic system. The previously known division into a plurality of heating elements furthermore has the disadvantage that the devices have to be switched differently at different rated voltages of the mains power in order not to reach any unpermittedly high power consumption.